A valuable asset to the irrigation industry has been the development of irrigation systems that travel while sprinkling large land areas with water and require virtually no personnel attention during operation. Substantial elimination of the labor costs that were earlier required has greatly enhanced the commercial success of large field irrigation. Although many different types of irrigation systems have been developed over the years, the type of irrigation system that is most prevalent is the circular irrigation system which incorporates a plurality of sprinkler pipe sections that are each supported by a mechanism for inducing movement to the pipe sections. In circular irrigation systems a central pivot tower is provided that also serves as a water supply and one extremity of the irrigation system is connected thereto causing the entire irrigation system to revolve about the pivot during continuous irrigation operations. Although circular irrigation systems have been quite successful, it is clear that greater crop yields and lower cost irrigation would be achieved if the irrigation system were capable of irrigating rectangular land areas or other specifically shaped land areas as opposed to circular areas. One attempt to accomplish more rectangular irrigation through the use of circular irrigation systems is through the use of corner irrigation spray devices that are activated only during four small segments of each revolution of the irrigation system. Although the increase of land area irrigation through the use of irrigation guns is not in unsubstantial, it would nevertheless be commercially desirable to provide an irrigation system that was capable of irrigating the entirety of a large rectangular land area.
In the past, irrigation systems have been developed for irrigation of rectangular fields, but in order to provide for proper operation of the irrigation system, it is generally deemed necessary that a plurality of tracks or guideways be provided in order to physically guide the irrigation system over the land area. Of the number of patented devices that have been developed with track or guideway control in mind, U.S. Pat. No. 3,608,827 to Kinkead is typically representive. Linearly movable irrigation systems have also been developed that do not necessitate the use of tracks or guideways such as taught by U.S. Pat. No. 3,613,703 to Stout which utilizes a guide rail 52 for reference during movement over a land area and traverses by alternate movement and pivoting of each of the ends of the system. In the case of the structure identified in the patent to Stout the ambulatory irrigation system is so arranged and controlled that each end of the composite line alternately can be caused to travel a predetermined distance along an arcuate path with the opposite end of the composite line temporarily being substantially at the center of curvature of the arcuate path and with the entire line thus swinging forwardly in alternate angular direction as it moves over the land area. More simply, one extremity of the irrigation system remains static and serves as a pivot during a portion of the movement and the sequence is then reversed causing the other extremity to remain static while the first extremity is caused to move. The ends of the system are not capable of simultaneous movement.
It is considered desirable to provide a linearly movable irrigation system that does not require a track or guideway to control movement thereof such as is the case with Kinkead U.S. Pat. No. 3,608,827 and which does not cause excessive water distribution on certain of the land section such as is likely to occur when each end of the irrigation system alternately moves forward.
Accordingly, it is a primary feature of the present invention to provide a novel linearly movable irrigation system that moves in substantially linear manner over a land area and is capable of irrigating the entirety of a generally rectangular land area or irrigating a land area of an irregular shape.
It is also a feature of the present invention to provide a novel linearly movable irrigation system whereby control of the movement of the system is accomplished by sensing means that respond in regard to the position of the irrigation system rerlative to an elongated reference.
It is an even further feature of the present invention to provide a novel linearly movable irrigation system that moves in linear manner over a land area and, in the event of the occurrence of predetermined misalignment of the irrigation system relative to the reference, the irrigation system is automatically self-correcting or self-steering to maintain its travel within a defined boundary.
It is also an object of the present invention to provide a novel linearly movable irrigation system employing a reference such as an elongated guide surface which may be straight or curved as desired, wherein the irrigation system is provided with a control mechanism that senses linear displacement and angular misalignment of the irrigation system relative to the reference for controlling travel of the irrigation system relative to the elongated reference.
It is also a feature of the present invention to provide a novel linearly movable irrigation system and wherein a plurality of individually supported and driven sections are incorporated into an elongated irrigation system and wherein movement of each of the sections is controlled by its angular relationship with an adjacent irrigation section, such angular relationship control being overridden under certain circumstances by control signals received from a power and control portion of the irrigation system.